$\dfrac{1}{8} - \dfrac{5}{3} = {?}$
$ = {\dfrac{1 \times 3}{8 \times 3}} - {\dfrac{5 \times 8}{3 \times 8}} $ $ = {\dfrac{3}{24}} - {\dfrac{40}{24}} $ $ = \dfrac{{3} - {40}}{24} $ $ = -\dfrac{37}{24}$